Comparative characterization of PIP nano-and microcomposites by in-mold shrinkage measurements and structural characteristics

Poly(propylene)-clay nanocomposites and poly(propylene) containing conventional inorganic fillers such as calcium carbonate (CaCO3) and glass fiber were used in a comparative study focusing on dimensional stability, structure, mechanical and thermal properties. Micro- and nanocomposites were prepared by melt blending in a twin-screw extruder. The relative influence of each filler was observed from dimensional stability measurements and structural analysis by WAXD, TEM, and thermal and mechanical properties. At equal filler loadings, PP/clay nanocomposites exhibit an improvement in dimensional stability and were the only composites capable of reduced shrinkage in both in-flow and crossflow directions. The flexural modulus of PP increased nearly 20% by compounding with 4% organoclay, as compared to a similar performance obtained by compounding with 10 wt.-% of CaCO3 or approximately 6 wt.-% of glass fiber. The HDT and thermal stability of PP were enhanced by using nanoclay as filler.